A residual gas burner is usually part of a fuel cell system. The fuel cell system additionally comprises at least one fuel cell, which comprises an anode and a cathode. For operating the fuel cell, an anode gas for the anode and a cathode gas for the cathode are necessary, which are fed to the cathode and to the anode respectively. Through the electrochemical reactions which take place in and/or on the anode and the cathode during the operation of the fuel cell, an anode waste gas and a cathode waste gas develop. The residual gas burner serves for the further usage of the cathode waste gas and of the anode waste gas, which are fed to the residual gas burner as educt gases. To this end, the residual gas burner comprises two educt gas feeds, which feed the respective educt gas to a combustion chamber of the residual gas burner. The respective educt gas feeds comprise outlet openings, through which the respective educt gas enters the combustion chamber where it is combusted. The heat created through the combustion of the educt gases can then be fed for example via a heat transfer device to the cathode gas upstream of the fuel cell in order to increase the efficiency of the fuel cell or of the fuel cell system. Disadvantageous here is that the residual gas burner, in particular due to a poor mixing-through of the educt gases in the combustion chamber, has a low efficiency. In addition, such residual gas burners are very heavy and through their design, are complex to manufacture.